Removable punch retainer



Oct. 23, 1956 w. E. JEWELL, JR

REMOVABLE PUNCH RETAINER Filed Aug.

x M 5 M W ZIHORNEYIS.

United States PatentC REMOVABLE PUNCH RETAINER William E. Jewell, Jr., Erdenheim, Pa., assignor to Engineering Service, Philadelphia, Pa., a partnership composed of Michael Gargaro, Jacob H. Finkelstein and William E. Jewell, Jr.

Application August 9, 1954, Serial No. 448,703 6 Claims. (Cl. 279-79) The present invention relates to retaining mechanism for punches, particularly of the character which are used to hold a plurality of punches which operate on the work simultaneously or successively and are placed in the same mounting plate.

A purpose of the invention is to reduce the cost and simplify the mounting and changing of punches.

A further purpose is to make it possible to mount punches closer together axially.

A further purpose is to mount punches without reducing the head space of the press.

' A further purpose is to mount a punch in the bore of a mounting plate by a resilient punch retainer which is held in the bore, suitably by a shoulder, and which provides a finger protruding diagonally in the general direction of the axis and inwardly away from the end of the mounting plate bore through which the punching end of the punch protrudes and to engage the finger in a longitudinal slot on the side of the punch.

-A further purpose is to split the resilient punch retainer longitudinally and resiliently urge it downwardly to sit in the bore of the mounting plate.

A further purpose is to taper the longitudinal slot in the punch so as to guide a tool to deflect the finger for removal of the punch.

A further purpose is to secure the punch against turning by a key extending through a slot at the end of the punch, the retainer and the mounting plate remote from the punching end of the punch.

A further purpose is to make the punch more readily removable and replaceable without removing the mounting plate.

'Furtherpurposes appear in the specification and in the claims. 4

In the drawings I have chosen to illustrate a few only of the numerous embodiments in which my invention may appear, selecting the forms'shown from the standpoints of convenience in illustration,satisfactory operation and clear demonstration of the principles involved.

Figure 1 is a central axial section of the punch retaining mechanism of the invention in punching position.

Figure 2 is an exploded perspective of the key, punch and punch retainer of Figure 1.

Figure 3 is a top plan view of the mounting plate, key punch retainer and punch, omitting the punch die.

Figure 4 is a section on the line 4-4 of Figure 1.

Figure 5 is a detached side elevation of the punch retainer and punch.

Figure 6 is a side elevation of the punch omitting the key slot.

Figure 7 is a section similar to a fragment of Figure 1 showing the insertion of a tool to remove the punch.

Figure 8 is a section corresponding to Figure 4 showing a punch retainer without an opening in the side.

Describing in illustration but not in limitation and referring to the drawings:

In the punching of metal sheet, plastic, cardboard and the like, it is common practice to set up a plurality of 2,767,990 Patented Oct. 23, 1956 punches in the mounting plate of a punch die. This is usual for the purpose of punching a number of holes in the work simultaneously, the holes having a predetermined spaced relationship to one another and being of desired sizes and shapes. In some cases, however, this is done for the purpose of sequentially punching the work or punching diiferent work at different positions.

Efforts have been made in the prior art to provide removable mountings for punches, to eliminate the necessity of disassembling the mounting plate every time a punch breaks or is to be changed for a punch of a different size or shape. These efforts have resulted in applying cumbersome spiral spring ball detents which normally extend out beyond the punch shank and restrict the head space. They also are bulky laterally and prevent bringing two punches close together axially. The devices of this kind furthermore are complicated and expensive.

The present invention is designed to provide a simple and inexpensive removable mounting for each individual punch of a multiplicity of punches. The invention could also be applied to a single punch. In accordance with the invention, the punch is held in a bore of a punch mounting plate which is surrounded by a resilient punch retainer of generally tubular form. The punch retainer is held in the mounting plate, preferably in a counterbore and shoulder on the bore.

The punch retainer has a recess at one side, suitably of horse-shoe form which separates a resilient finger from the material of the punch retainer Wall, and allows the resilient finger to protrude longitudinally of the axis and inwardly so as to engage in the end of a longitudinal slot in the side wall of the punch. The slot is preferably tapering or diverging away from the axis, so that a tool of wedge character extending up through the slot can force the finger out of the slot and release the punch.

The punch retainer may be fully tubular, but preferably has an opening at one side and is resiliently urged outwardly to grip the wall of the counterbore.

Where the punch has to be accurately positioned against rotation, the punch, the punch retainer and the mounting plate desirably are provided with a diametral slot at the end of the punch remote from the punching end, which receives a key.

It will thus be evident that the punch is readily removable without separating the mounting plate, and an individual punch can be replaced at will without delay.

The device is thus very simple, convenient and inexpensive both to make and to install. No structure is required to be mounted on the lower face of the mounting plate, as in the prior art.

No dowels and no screws need be attached.

By the present invention punches can be placed very closely beside one another. They can be successively mounted with as little as d inch between the shanks of the respective punches.

Considering first the form of Figures 1 to 5, a typical piercing punch and die is shown having an upper punch die 20, and a punch mounting plate 21 secured thereon. The punch unit cooperates with a lower female die block 22 which is mounted on a die shoe 23. A hold-down or stripper plate 24 is provided to hold down the work, not shown.

The punch unit and the female die are moved relatively toward one another, suitably moving the punch up and down While the female or lower die is stationary.

The mounting plate has at each punch location a suitably vertical bore 25 which receives a punch 26. The punch has a shank 27 desirably of uniform cylindrical form which extends into the bore 25, and a reduced punching end 28 which extends through an opening 30 in the hold-down or stripper plate and enters the opening 31 in the female die. The female die has a drop-thru or slug recess 32 and the die shoe has a corresponding drop-thru or slug recess 33.

The bore 25 which receives the punch has at its upper portion a counterbore 34, slightly larger, forming a shoulder 35. The counterbore receives and snugly holds a tubular punch retainer 36, suitably of spring steel or spring brass. The retainer engages at its upper end against the bottom of the punch die 20 and at its lower end against the shoulder 35.

The retainer has a lateral cutout suitably of horseshoe form at 37 forming a spring finger 38 which extends axially and protrudes inwardly, as best seen in Figure l, engaging in a longitudinal slot 40 in the punch to lock the punch by seating against the shoulder 41 at the end of the slot. The punch slot desirably tapers or diverges away from the axis of the punch as shown in Figure 1, so that the bottom 42 of the slot and the finger 38 are converging when the finger is seated in the slot.

The punch retainer can be fully tubular as shown in Figure 8, but it preferably has an opening 43 extending longitudinally of one side, permitting the retainer to be formed from sheet metal. The tubular wall is outwardly resilient and slightly larger than the counterbore, so that when the retainer is forced into the counterbore at a time when the mounting plate is removed from the punch die, the tubular wall of the retainer 36 firmly grips the counterbore and holds the retainer in place.

In some cases the punch need not be located angularly, and the top of the punch may merely be flat and bevelled as shown at 44 in Figure 6.

Where, however, the punch is to punch a special shape, such as an oval, square, diamond, cross or the like, location angularly is often important. For this purpose the punch shank at the end opposite to the punching end 28 is provided with a diametral slot 45, and cooperating diametral slots 46 are provided at the upper end of the punch retainer, and also cooperating diametral slots 47 are provided in the mounting plate. A suitably rectangular key 48 is carried across through cooperating slots, and is held in place by being located between the punch die and the mounting plate so as to secure the punch retainer and punch against turning.

To assemble the structure in the first place, the mounting plate is removed, the punch retainers are inserted with the keys and the mounting plate is reassembled on the punch die. Punches are then forced up into the bore and they deflect the spring finger which later seats in the groove and holds the punch in place.

When a punch is to be changed, a suitably wedgeshaped tool 50 is forced up in the slot and the taper of the slot tends to jam the tool outwardly and deflect the sleeve finger until it leaves the slot. The punch can then be pulled out from below and replaced without removing the mounting plate.

A wide variety of diiferent sizes of punch can be mounted, but for many purposes a standard shank and punch retainer can be used with a variety of different sizes of punch.

In view of my invention and disclosure variations and modifications to meet individual whim or particular need will doubtless become evident to others skilled in the art, to obtain all or part of the benefits of my invention without copying the structure shown, and I, therefore, claim all such insofar as they fall within the reasonable spirit and scope of my claims.

Having thus described my invention, what I claim as new and desire to secure by Letters Patent is:

l. A punch retaining mechanism, comprising a punch mounting plate having a bore adapted to receive a punch, in combination with a resilient generally tubular punch retainer engaged in the bore, and having a cut-out fingershaped opening at one side of the retainer and a resilient finger extending generally axially and inwardly of the bore away from the end of the bore from which the punch will protrude, and a punch which is removably engaged in the bore on the inside of the retainer, has a generally axial slot extending inwardly of the bore from at least said end of the bore, accessible from the outside thereof, and terminating in a shoulder, and has the finger of the retainer engaged in the slot against the shoulder.

2. A punch retaining mechanism according to claim 1, in which the retainer is open at one side and resiliently urged outwardly to engage the inner walls of the bore.

3. Apunch retaining mechanism according to claim 1, in which the punch retainer is held in a counterbore which provides a shoulder against the bore and secures the punch retainer against removal.

4. A punch retaining mechanism according to claim 1, in which the slot is tapered and diverges further from the axis as it progresses toward the end of the finger.

S. A punch retaining mechanism according to claim 1, in which there is a transverse slot through the top of the mounting plate, the retainer and the end of the punch remote from the punching end, and a key extends through the transverse slot and secures the punch against rotation.

6. A punch retainer according to claim 1, in. combination with a wedge-shaped tool protruding into the slot and wedging the finger outwardly to a position at which the punch can be withdrawn.

References Cited in the file of this patent UNITED STATES PATENTS 1,354,549 Gilmer Oct. 5, 1920 1,974,464 Leins Sept. 25, 1934 2,153,950 Whinery Apr. 11, 1939 2,171,361 Gits Aug. 29, 1939 2,215,015 Richard Sept. 17', 1940 2,309,713 Ratkowski Feb. 2, 1943 2,479,150 Boraski Aug. 16, 1949 2,496,700 Cole Feb. 7, 1950 

